This application, Diffusion Tensor Imaging in Sexually Abused Children (SAC)is a proposal to supplement the NIMH funded study, "PTSD & Childhood Sexual Abuse: Psychobiology," RO1-MH63407. The parent proposal is a 5-year cross-sectional investigation with a one-year prospective follow-up to non-invasively examine the psychobiology of childhood posttraumatic stress disorder (PTSD) secondary to sexual abuse. In the parent study, we are examining the diagnosis and severity of PTSD on outcomes of biological stress system regulation and brain maturation. We will study 3 groups of 70 children (35 males/35 females) aged 6 to 12 years: children with PTSD secondary to sexual abuse, SAC without PTSD, and non-traumatized age and sociodemograghically comparable controls. Biological stress system regulation will be assessed by 24-hour urinary catecholamine and free cortisol levels. Brain maturation will be assessed by: magnetic resonance spectroscopy-based brain N-acetylaspartate concentrations, which reflect neuronal integrity, magnetic resonance imaging-based brain morphometry (cerebral, and amygdala/hippocampal volumes and corpus callosum (CC) area), and cognitive function. Although the parent grant examines cortical myelination through MRI-based morphometry, the present grant supplement proposes to enhance our measurements of cortical myelination and other microstructural aspects of brain development by adding an additional MRI acquisition protocol to our existing morphometric MRI scan, diffusion-weighted imaging (DWI). DWl is a functional neuroimaging mode which measures brain water-diffusion characteristics reflecting axon density and myelin abnormalities. It also permits enhanced discrimination of brain injuries involving sheering, contusion, and other manifestations of head trauma. DWl will assist in determining which SAC may have had other reasons than sexual abuse for adverse brain development. We hypothesize that compared with controls, SAC will show water-diffusion characteristics on DWl consistent with (1) decreased myelination and (2) slower age-related growth of the CCo We also hypothesize that (3) SAC with PTSD will show DWl characteristics reflecting decreased myelination and slower CC growth compared with SAC without PTSD. The study will enhance our knowledge of neuroanatomical/neuropsychological concomitants of sexual abuse in exchange for additional image analysis. [unreadable] [unreadable]